Evecuated solar panel with a non evaporable getter pump

ABSTRACT

The evacuated solar panel ( 1 ) comprises a frame ( 2 ) containing a plurality of spacers ( 3 ) carrying a transparent wall ( 4 ). The transparent wall ( 4 ) with the frame ( 2 ) defines a closed chamber ( 6 ) containing the spacers ( 3 ), the light absorber ( 8 ) and a getter pump ( 15 ). The getter pump ( 15 ) comprises an envelope having selectively blackened outer surfaces ( 16 ) and including one or more non-evaporable getter NEG elements.

The present invention relates to an evacuated solar panel with a Getter pump, in particular according to the invention the getter pump is a Non-Evaporable Getter (NEG) pump.

As known in the art, NEG pumps are widely used to maintain the vacuum inside sealed evacuated devices.

In the NEG pumps the gas molecules are adsorbed on the surface of the getter material, resulting in NEG saturation.

To avoid saturation by the pumped gases and, thus, loss of the pumping effect (i.e. capability of adsorbing gases molecules) NEG must be heated to help the adsorbed gases molecules to diffuse from the surface of the getter pump within the volume of the same.

Heating may be applied continuously or intermittently for instance by means of electric heating.

Nevertheless such electric heaters require electric vacuum feedthroughs, which add costs to the device and reduce its reliability.

The technical aim of the present invention is therefore to provide an evacuated solar panel with a NEG pump by which the said problems of the known art are eliminated.

Within the scope of this technical aim, an object of the invention is to provide a solar panel which is cheap when compared to the solar panels of the known art.

Another object of the invention is to provide a solar panel which is very reliable.

The technical aim, together with these and further objects, are attained according to the invention by providing an evacuated solar panel with a NEG pump in accordance with the accompanying claims.

Advantageously, in case of solar panels solar heating is freely available and the non evaporable getter pump is contained in a volume enclosed by selectively blackened walls, so as to effectively absorb the solar light and reach the temperature required for gas diffusion. This temperature varies for different NEG pumps and operating pressures, but in all cases it should not be lower than about 180° C.

Further characteristics and advantages of the invention will be more apparent from the description of a preferred but non-exclusive embodiment of the evacuated solar panel with a getter pump according to the invention, illustrated by way of non-limiting example in the accompanying drawings, in which:

FIG. 1 is a schematic view of a portion of a solar panel having a getter pump according to the invention;

FIG. 2 is a prospective view of a getter pump of the solar panel according to the invention;

FIG. 3 show a different embodiment of the solar panel with a getter pump according to the invention; and

FIG. 4 schematically shows a solar panel having the getter pump of the invention.

With reference to the figures, these show an evacuated solar panel generally indicated by the numeral reference 1.

The solar panel 1 comprises a frame 2 which generally carries a plurality of spacers 3 carrying an upper transparent glass wall 4 and a back lower wall 2 a made of a metal or of a glass sheet.

The frame 2 with the transparent wall 4 and the back wall 2 a defines a closed chamber 6 containing the spacers 3 and an absorber 8.

As known in the art the adsorber 8 comprises one or more adsorbing panels 10 and one or more cooling pipes 11 connected thereto.

The chamber 6 also contains a NEG pump 15 which advantageously comprises an envelope having outer selectively blackened surfaces 16 and including therein one or more non-evaporable getter elements.

The envelope has a box-like shape and has preferably one through opening 18 for keeping the inner volume of the box-like envelope in contact with the outside (i.e. with the chamber 6) of the box-like envelope.

Different opening geometries could also be envisaged.

In a first embodiment, the envelope is thermally independent of the solar panel (FIG. 1).

In this respect the envelope is provided with thermally insulating connecting elements 20 to the absorber (i.e. to the adsorbing panel 10) or to the frame 2 or to the spacers 3 of the solar panel 1.

Thus the non-evaporable getter pump is suspended via springs to minimize the thermal conduction to the anchoring points, which could then be warm (adsorber) or cold (panel frame or spacers) so as to largely exceed 180° C. in good insolation conditions, no matter what panel operating temperature is chosen.

These thermally insulating connecting elements 20 comprise metal springs or wires.

In particular, the absorbing panel 10 defines a cavity 22 wherein the envelope is inserted.

In a second embodiment the envelope is thermally in contact with the absorber (FIG. 3).

In this respect the absorbing plate 10 of said absorber 8 defines at least one wall 25 of the envelope which contains the NEG elements, an opposite wall 26 of this envelope being defined by a plate connected mechanically or welded to the absorbing panel.

This configuration may be advantageously used when the operating absorber temperature exceeds 180° C., nevertheless it may also be adopted for lower operating temperatures, provided that the circulation of the cooling fluid be intermittently stopped so as to let the absorber temperature increase to higher values (to regenerate the getter pump). This operating mode may turn out to be very helpful if existing panels must be adapted for a different use.

In this respect the solar panel of the invention comprises a control system arranged for intermittently stopping the circulation of the cooling fluid within the cooling pipe.

Advantageously both non-evaporable getter pumping speed and the gas load increase in phase with the increase of the incident solar power.

The embodiment above described is provided with two transparent walls, i.e. the transparent wall 4 and the back wall 2 a whenever preferably used in connection with reflecting mirrors.

A different embodiment (to be used without such reflecting mirrors) may have the transparent back wall 2 a replaced by a metal wall.

The solar panel with a getter pump conceived in this manner is susceptible to numerous modifications and variants, all falling within the scope of the inventive concept; moreover all details can be replaced by technically equivalent elements.

In practice the materials used and the dimensions can be chosen at will according to the requirements and to the state of the art. 

1. Evacuated solar panel with a getter pump, said evacuated solar panel comprising a frame carrying a plurality of spacers carrying at least a transparent wall, said transparent wall defining with said frame a closed chamber containing said spacers and an absorber and a getter pump, wherein said getter pump comprises an envelope having outer selectively blackened surfaces and including one or more NEG elements.
 2. Evacuated solar panel as claimed in claim 1, wherein envelope has a box-like shape and has at least one through opening for keeping the inner volume of the box-like envelope in contact with the outside of the box-like envelope.
 3. Evacuated solar panel as claimed in claim 1, wherein said envelope is thermally independent of the solar panel.
 4. Evacuated solar panel as claimed claim 3, wherein said envelope is provided with thermally insulating connecting elements to the absorber or to the frame or to the spacers of the solar panel.
 5. Evacuated solar panel as claimed in claim 1, wherein said thermally insulating connecting elements comprise springs.
 6. Evacuated solar panel as claimed in claim 1, wherein said absorber comprises one or more absorbing panels and one or more cooling pipes connected thereto, the absorbing panel defining a cavity where said envelope is inserted.
 7. Evacuated solar panel as claimed in claim 1, wherein said envelope is thermally in contact with the absorber.
 8. Evacuated solar panel as claimed in claim 1, wherein an absorbing plate of said absorber defines at least one wall of said envelope which contains the NEG elements, an opposite wall of said envelope being defined by a plate connected to the absorbing panel.
 9. Evacuated solar panel as claimed in claim 1, further comprising a control system arranged for intermittently stopping the circulation of the cooling fluid within the cooling pipe. 